Method for realizing backpressure of masses of ports and device thereof

ABSTRACT

A method for realizing backpressure of masses of ports and a device realizing the method are disclosed. The method for realizing backpressure of masses of ports includes: detecting whether user data transmitted to a channelized physical port reaches a backpressure threshold, generating an idle frame or a series of idle frames when the backpressure threshold is reached; combining the idle frame with the user data which needs to be transmitted to the channelized physical port reaching the backpressure threshold, and transmitting the combined data; discarding the idle frame before the combined data enters the channelized physical port. The idle frame is employed in the present invention to realize the backpressure. The idle frame occupies some of the transmission bandwidth and reduces the bandwidth of user data, while the idle frame does not enter the physical port. Therefore, the aim of backpressure is achieved. The bandwidth of idle frame can be pre-configured according to the requirements. After the idle frame is generated, its bandwidth can be increased or decreased smoothly based on the existence of the backpressure. The control is very easy and convenient.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2007/071217, filed Dec. 11, 2007, which claims the benefit ofChinese Patent Application No. 200710001124.1, filed Jan. 18, 2007, bothof which are hereby incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to a control technique for backpressure ofnetwork ports, and more specifically, to a method for realizingbackpressure of masses of ports and a device thereof.

BACKGROUND

Currently, with evolution of the network, specifically with hugeapplications on streaming media, there is a demand for a higher anddifferentiated performance of Quality of Service (QoS) in the network.No matter which policy is adopted to realize the QoS of the network,finally at several key nodes of the network, it should be capable ofscheduling a plurality of sources to be scheduled (the source isgenerally a queue), based on pre-configured parameters (bandwidth,jitter, etc.), and transmitting data selected from an appropriate queue.When congestion occurs and packets need to be discarded, then thepackets are discarded based on pre-configured parameters of CommittedInformation Rate/Peak Information Rate (CIR/PIR) priority, etc.

There are diverse selections on several queues scheduling, for example,Strict-Priority Queue (PQ) scheduling, Round Robin (RR) scheduling,improved Weighted Round Robin (WRR) scheduling, Weighted Fair Queue(WFQ) scheduling, etc. No matter which scheduling method is utilized,backpressure is always a headache. As to scheduling a plurality ofqueues, generally, reservation for bandwidth needs to be configured, forexample, the bandwidth of queue A is 10 Mbps, the bandwidth of queue Bis 1 Gbps, the bandwidth of queue C is 200 Mbps, etc. To achieve linerate forwarding performance, the sum of all reserved bandwidth of thequeues may exceed or be equal to the final export bandwidth. At thistime, there is a new inevitable problem caused by burst traffic orschedule offset, etc., i.e. the total allowable export traffic (1 Gbpsor 2.5 Gbps, for example, which is limited to actual physical export,)is lower than the sum of actual bandwidth of all queues. As such, it isimpossible to satisfy the actual bandwidth of all queues. A desirableinstance may be as follow.

In a first instance, if total bandwidth of actual data does not exceedtotal export bandwidth, then it is desirable to perform scheduling basedon the reserved bandwidth which is actually configured, and nobackpressure occurs.

In a second instance, if transient burst traffic occurs on the actualdata, which exceeds the total export traffic during some time period, atthis time, caching may be performed in the export queues after exportcongestion occurs. When total bandwidth of the actual data is lower thanexport bandwidth, data in the cache may be transmitted, and also nobackpressure occurs at this time.

In a third instance, if total bandwidth of actual data is always higherthan total export bandwidth during quite a long time, then backpressuremay occur. However, it is desirable that backpressure has effects on allqueues participating in scheduling, and moreover, it is better to assignthe effects according to reserved bandwidth proportion. That is to say,the actual scheduling bandwidth of queues participating in scheduling isbetter to shrink according to the reserved bandwidth proportion. Not allqueues participate in bandwidth assigning. Rather, bandwidth assigningis performed among queues with actual data which are to be scheduled.

Currently, conventional standard QOS scheduling module is illustrated asFIG. 1, with four levels of scheduling in all. Firstly, differentservices are identified among users internally, and WFQ+SP (StrictPriority) scheduling is performed among different services. Then,CIR/PIR may be configured by the user, i.e. a committed bandwidth isprovided for the user, and to a certain extent, burst traffic of user isallowed to pass. Next, the user may be mapped to different priorityqueues in the ports or different internal services of the user may bemapped to priority queues in the ports, and the priority levels arescheduled according to PQ scheduling. Finally, RR scheduling or WRRscheduling is performed among the ports. A module which accomplishes QOSfunction as illustrated in FIG. 1 may be referred to as a trafficmanagement module. Generally, number of ports is in accordance withnumber of physical channels. Backpressure of physical channels may bedelivered directly to ports. Then the ports deliver backpressurereversely in turn. At this time, the packets are cached in the trafficmanagement module. When cache is full, the packets are discardedaccording to parameters of priority, CIR or PIR configured by the user,etc. In the case of guaranteeing user CIR, ensure that packets with highpriority are scheduled first and packets with low priority are discardedfirst. Currently, conventional art usually inquires transmitting FirstIn First Out (FIFO) status actively from a physical transmitting portvia a traffic management module, or the physical transmitting port feedsback transmitting FIFO status actively to the traffic management module.If the transmitting FIFO exceeds backpressure threshold, the physicaltransmitting port outputs a backpressure signal to the trafficmanagement module. The traffic management module stops transmitting andthen caches packets in the scheduling queue. If the queue is full, thenthe packets are discarded according to the pre-configured parameters.

When there are too many physical channels, (for example, channelized POS(packet over SDH/SONET; where: SDH represents Synchronous DigitalHierarchy; SONET represents Synchronous Optical NETwork) ports may have1k physical ports), when egress of the traffic management module, forexample, SPI4.2 port may only support 256 channels of backpressuresignals, cannot respond to backpressure of all channels, negativefeedback of backpressure cannot be formed. That is, according to theexisting solution and interface specification, backpressure signals ofmasses of ports cannot be transmitted. Then, according to the existingtechnique, the egress rate is limited only through open loop control,i.e. shaping egress to limit its egress rate to be less than or be equalto physical port rate. With this technique, backpressure of physicalchannel is avoided, and fluctuation resulted from traffic variation issolved within the traffic management module internally. This method hasthree problems in actual application:

Common traffic management module inevitably has scheduling offset as tosome packets with a fixed length when performing traffic scheduling.Such scheduling offset may cause transmitting queue congestion inphysical ports, i.e. it may discard the packets when physical egressqueue is full. Thus, configured parameters of user CIR and priority,etc. cannot be guaranteed.

In addition, shaping granularity of egress may not satisfy practicalrequirements, for example, the bandwidth of a low speed port is 64kwhile the shaping granularity of egress is 20k. If line rate of port isguaranteed, then shaping PIR has to be configured at 80k. If there is noresponse to the backpressure, the packets may be discarded. At thistime, discarding packets on the physical ports usually has to beperformed as tail discarding or discarding according to the absolutepriority. Thus, the configured parameters of user CIF and priority, etc.cannot be guaranteed.

Moreover, current channels transmitting backpressure signals of massesof ports are customized backpressure state bus, and there is no unifiedstandard. Therefore, a common practice is to use a set of products,manufactured by the same factory as the physical port and trafficmanagement module, to achieve backpressure of masses of ports.Consequently, the applications of the backpressure of masses of portsare limited, or cannot be applied to a developed system.

There are other solutions to achieve backpressure in conventional art.For example, the traffic management module is accomplished by a commonCPU. By using CPU to forward data, the CPU directly inquiresbackpressure status of channels via control channel, thus avoiding thelimit of number of channels.

When CPU participates in forwarding process, the forwarding performanceis limited by the CPU capacity. Moreover, the CPU also participates incontrol plane processing, which results in a complexity of CPU procedureand a poorer reliability of CPU. In addition, as there are too manychannels, CPU cannot handle backpressure in time, i.e. CPU cannotsatisfy line rate forwarding in the case that there are relatively lotsof channels.

SUMMARY

In order to solve the drawback of failure to realize backpressure ofmasses of ports in prior art, the present invention provides a methodfor backpressure of masses of ports and a device thereof The presentinvention has a high rate of backpressure and may satisfy the need forlow speed port delay. There is no need for CPU to participate, thus theforwarding performance is not affected by CPU performance. Moreover, thepresent invention can be conveniently applied to various existingsystems.

A technical solution utilized by an embodiment of the present inventionto solve the technical problem is a method for realizing backpressure ofmassed of ports. The method includes:

detecting whether user data transmitted to a channelized physical portreaches a backpressure threshold, generating an idle frame or a seriesof idle frames when the backpressure threshold is reached;

combining the idle frame with the user data which needs to betransmitted to the channelized physical port reaching the backpressurethreshold, and transmitting the combined data; and

discarding the idle frame before the data combined from the idle frameand the user data, enters the channelized physical port.

A device for realizing backpressure of massed of ports is also providedaccording to one embodiment of the present invention. The deviceincludes:

a detecting module, configured to detect whether user data transmittedto a channelized physical port reaches a backpressure threshold andtransmit a massage if the backpressure threshold is reached;

an idle frame generating module, configured to generate an idle frame ora series of idle frames after receiving the massage;

a downstream queue scheduling module, configured to combine the idleframe with the user data which needs to be transmitted to thechannelized physical port reaching the backpressure threshold, andtransmit the combined data;

a downstream forwarding module, configured to transmit the combineddata, transmitted by the downstream queue scheduling module, to thechannelized physical port reaching the backpressure threshold; and

a frame discarding module, configured to discard the idle frame beforethe combined data enters the channelized physical port reaching thebackpressure threshold.

Embodiments of the present invention utilize idle frame to realizebackpressure, The idle frame occupies some of transmission bandwidth andreduces bandwidth of user data. The idle frame is discarded beforeentering the physical port such that the idle frame does not enter thephysical port. Therefore, the aim of backpressure is achieved.

The problem that too many channels result in failure of deliveringbackpressure to the traffic management module can be solved according toembodiments of the present invention. As such, problem of backpressure,whether caused by scheduling inaccuracy of the traffic management moduleor by burst traffic occurring on user data, can be effectively solved bysolutions in the embodiments of the present invention. With solutions inthe embodiments of the present invention, it is quick to deliverbackpressure and easy to use, and the present invention can be appliedto various existing systems conveniently.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a method for realizing backpressure inconventional art;

FIG. 2 is a schematic flowchart of a method for realizing backpressureof masses of ports according to one embodiment of the present invention;

FIG. 3 is a schematic flowchart of a method for realizing backpressureof masses of ports according to another embodiment of the presentinvention;

FIG. 4 is a structural schematic diagram of a device for realizingbackpressure of masses of ports according to one embodiment of thepresent invention; and

FIG. 5 is a structural schematic diagram of a device for realizingbackpressure of masses of ports according to another embodiment of thepresent invention.

DETAILED DESCRIPTION

The purposes, technical solutions and advantages concerning theembodiments of the present invention may become more readily appreciatedby reference to the following description of the embodiments, when takenin conjunction with the accompanying drawings.

FIG. 2 illustrates a schematic flowchart of a method for realizingbackpressure of masses of ports according to one embodiment of thepresent invention. The method for realizing backpressure of masses ofports in the embodiment includes the following steps.

Step 201: Data traffic transmitted to a channelized physical port isdetected. For example, detection for transmitting data traffic isrealized by detecting transmission buffer status of channelized physicalport.

Step 202: Data traffic is determined. That is, it is determined whetherthe transmission buffer reaches a backpressure threshold. If thetransmission buffer reaches a backpressure threshold, step 203 isperformed. If the transmission buffer does not reach a backpressurethreshold, step 201 is performed.

Step 203: An idle frame or a series of idle frames are generated.

Step 204: The idle frame is combined with the user data transmitted tothe channelized physical port reaching the backpressure threshold. Thepriority of the idle frame may be configured as high. The combined datamay be transmitted to a traffic management module for scheduling. Thetraffic management module may discard the received data in case ofcongestion, etc. The traffic management module may discard dataaccording to the priority level. For example, if an idle frame is of ahigh priority level, then the traffic management module first discardsthe user data in the combined data.

Step 205: The combined data combined from the idle frame and the userdata, is transmitted to the channelized physical port reaching thebackpressure threshold.

Step 206: The idle frame is discarded before the idle frame and userdata enter the channelized physical port.

At step 203, an initial bandwidth value of the generated idle frame maybe pre-configured. For example, the initial bandwidth value of idleframe is set as a scheduling offset of a queue where the idle frame islocated.

In this embodiment, a method for generating idle frame is utilized torealize backpressure of port. The idle frame is utilized to preemptbandwidth, thereby forcing the bandwidth of user data to decrease.Before entering the channelized physical port, the idle frame may bediscarded rather than enter the channelized physical port. Only the userdata with a reduced bandwidth enters the channelized physical port.Therefore, the aim of backpressure is achieved. Consequently,embodiments of the present invention embrace advantages of simple andeasy implementation, well adaptation to the number of ports, andcapability of realizing the backpressure of masses of ports, etc.

FIG. 3 illustrates a schematic flowchart of a method for realizingbackpressure of masses of ports according to another embodiment of thepresent invention. In this embodiment, before data traffic ofchannelized physical port is detected, each parameter is configured, inorder to improve operation efficiency of the whole system. Specifically,the process includes the following steps.

Step 301: A user queue for use by an idle frame is reserved for eachchannelized physical port (or the channelized physical port whichrequires a backpressure). The method proceeds to perform step 302.

Step 302: A CIR value of the above mentioned user queue for use by anidle frame is configured as scheduling offset. For example, atransmitting rate of physical port is 64K, and a scheduling offset is5%. A shaping granularity of port may be configured as 64K to satisfythe requirement. Then the CIR value of the user queue for use by an idleframe should be configured as 64K*5%=3.2K. If the granularity cannotsatisfy the requirement, when a shaping granularity of port is 20K, theCIR value should be configured as 20K*4-64K+80K*5%=20K.

Step 303: An initial bandwidth value of an idle frame is configured. Forexample, an initial bandwidth value of an idle frame of a channel of 64Kshould be configured as 64K*5%=3.2K. If taking granularity factor intoconsideration, when a granularity is 20K, the initial bandwidth value ofan idle frame may be configured as 20K*4-64K+80K*5%=20K.

Step 304: The transmission buffer of channelized physical portcorresponding to a certain user data is inquired.

Step 305: It is determined whether the transmission buffer ofchannelized physical port reaches backpressure threshold. If thetransmission buffer of channelized physical port reaches backpressurethreshold, step 306 is performed. If the transmission buffer ofchannelized physical port does not reach backpressure threshold, step304 is performed.

Step 306: An idle frame or a series of idle frames are generated. Thebandwidth value of the idle frame is the initial bandwidth valueconfigured in step 303. The generated idle frame is stored in a userqueue for use by the idle frame.

Step 307: The idle frame in the user queue for use by the idle frame iscombined with the user data in the channelized physical port reachingthe backpressure threshold.

Step 308: The combined data combined from the idle frame and the userdata is transmitted to the channelized physical port reaching thebackpressure threshold.

Step 309: The idle frame is discarded before the combined data combinedfrom idle frame and user data enters the physical port.

If backpressure still exists after the idle frame is generated, thenincrease the bandwidth of the idle frame. If backpressure disappears,then reduce the bandwidth of the idle frame until the bandwidth of theidle frame turns to zero. The increase or decrease may be performedsmoothly when increasing or decreasing the bandwidth of the idle frame.One of examples is to increase or decrease a certain amount of bandwidth(e.g. 1k) within each time unit (e.g. 1 second). If backpressure stillexists or has disappeared, then a certain amount of bandwidth isincreased or decreased again in a next time unit.

Compared with the previous embodiment, before backpressure threshold ofeach channelized physical port is detected, a CIR value of a user queuefor use by an idle frame is configured. When the user data of a certainchannelized physical port is found reaching a backpressure threshold,pre-configured parameters can be invoked directly. Thus operationefficiency is improved. In addition, detection for backpressurethreshold of channelized physical port is realized by detecting whetherthe transmission buffer of channelized physical port reaches thebackpressure threshold. If user data traffic is greater than totaltraffic of egress within a certain time period while transmission bufferhas not reached the backpressure threshold, then no backpressure isperformed. Thus, the situation that frequent backpressure affectsstability of user network can be prevented.

Referring to FIG. 4, a device for realizing backpressure of masses ofports according to one embodiment of the present invention, includes thefollowing modules:

a detecting module 401, configured to detect whether user datatransmitted to a channelized physical port reaches a backpressurethreshold, and transmit a massage to an idle frame generating module 403if the backpressure threshold is reached;

an idle frame generating module 403, which is located in a transmittingstart port of the user data and configured to generate an idle frame ora series of idle frames when receiving a massage transmitted by thedetecting module 401 indicating that the user data reaches thebackpressure threshold.

a downstream queue scheduling module 404, configured to combine an idleframe generated by the idle frame generating module with the user data,and transmit the combined data in a downstream direction (a directionfrom a transmitting end to a receiving end of user data) to a downstreamforwarding module;

a downstream forwarding module 405, configured to transmit the datawhich is combined from the idle frame and the user data and transmittedby the downstream queue scheduling module 404, to the channelizedphysical port reaching the backpressure threshold; and

a frame discarding module 406, configured to discard the idle framebefore the data, combined from the idle frame and the user data, entersthe channelized physical port reaching the backpressure threshold.

In another embodiment of the invention, a configuration module 402configured to configure an initial bandwidth value of idle frame mayalso be included. The bandwidth of idle frame generated by the idleframe generating module 403 is the initial bandwidth value configured bythe configuration module 402.

In this embodiment, the idle frame generating module may be located in atransmitting start port of user data. After being generated, the idleframe is combined with the user data by the downstream queue schedulingmodule and is transmitted to the channelized physical port by thedownstream forwarding module. In this embodiment, generating idle frameis utilized to realize backpressure of port. The idle frame is utilizedto preempt bandwidth, thereby, the bandwidth of user data is forced todecrease. Before entering the channelized physical port, the idle framemay be discarded rather than enter the channelized physical port. Onlythe user data with a reduced bandwidth enters the channelized physicalport. Therefore, the aim of backpressure is achieved. Consequently,embodiments of the present invention embrace advantages of simple andeasy implementation, well adaption to the number of ports, andcapability of realizing the backpressure of masses of ports, etc.

In another embodiment of the present invention, the device for realizingbackpressure of masses of port may also be realized by structuresillustrated in FIG. 5. The device includes:

a detecting module 501, configured to detect whether user datatransmitted to a channelized physical port reaches a backpressurethreshold, and transmit a massage to an idle frame generating module 503if the backpressure threshold is reached;

an idle frame generating module 503 located in a transmitting end portof user data, configured to generate an idle frame or a series of idleframes when receiving a massage transmitted by the detecting module 501indicating that the user data reaches the backpressure threshold;

an upstream forwarding module 504, configured to forward the idle framegenerated by the idle frame generating module in an upstream direction(a direction from a receiving end to a transmitting end of user data) toan upstream queue scheduling module 505;

an upstream queue scheduling module 505, configured to forward the idleframe transmitted by the upstream forwarding module 504 to a downstreamqueue scheduling module 506;

a downstream queue scheduling module 506, configured to combine the idleframe generated by the upstream queue scheduling module 505 with theuser data, and transmit the combined data to a downstream forwardingmodule 507;

a downstream forwarding module 507, configured to transmit the data tothe channelized physical port reaching backpressure threshold, where thedata is combined from the idle frame transmitted by the downstream queuescheduling module 506 and the user data; and

a frame discarding module 508, configured to discard the idle framebefore the data enters the channelized physical port, where the data iscombined from the idle frame and the user data and transmitted by thedownstream forwarding module 507.

In another embodiment of the invention, a configuration module 502,configured to configure an initial bandwidth value of idle frame mayalso be included. The bandwidth of idle frame generated by the idleframe generating module 503 is the initial bandwidth value configured bythe configuration module 502. In the forwarding process for idle frameby the upstream forwarding module 504 and the upstream queue schedulingmodule 505, the upstream forwarding module 504 and the upstream queuescheduling module 505 perform transparent transmission merely for theidle frame.

In this embodiment, the idle frame generating module is located in thetransmitting end port of user data. After being generated, the idleframe is forwarded by the upstream forward module and the upstream queuescheduling module to the downstream queue scheduling module first. Thenthe idle frame and the user data are combined by the downstream queuescheduling module and are transmitted to the channelized physical portby the downstream forwarding module. The upstream forwarding module andthe upstream queue scheduling module are existing modules in prior art.Similarly, this embodiment utilizes a method of generating idle framefor realizing backpressure of ports. The idle frame is utilized topreempt bandwidth, thereby forcing the bandwidth of user data todecrease. Before entering the channelized physical port, the idle framemay be discarded rather than enter the channelized physical port. Onlythe user data with a reduced bandwidth enters the channelized physicalport. Therefore, the aim of backpressure is achieved. Consequently,embodiments of the present invention embrace advantages of simple andeasy implementation, well adaptation to the number of ports, andcapability of realizing the backpressure of masses of ports, etc.

The software involved in the embodiments of the present invention may bestored in a computer readable storage medium.

The foregoing are merely exemplary embodiments of the present invention,while the scope of the present invention is not so limited. Anyvariations or equivalents can be readily appreciated by those skilled inthe art. These variations or equivalents shall be construed as fallingwithin the scope of the present invention.

1. A method for realizing backpressure of masses of ports, comprising:detecting whether user data transmitted to a channelized physical portreaches a backpressure threshold, generating an idle frame or a seriesof idle frames when the backpressure threshold is reached; combining theidle frame with the user data which needs to be transmitted to thechannelized physical port reaching the backpressure threshold, andtransmitting the combined data; and discarding the idle frame, beforethe combined data combined from the idle frame and the user data entersthe channelized physical port.
 2. The method of claim 1, wherein thestep of generating an idle frame or a series of idle frames furthercomprises: storing the idle frame in a user queue employed by the idleframe and reserved for the channelized physical port.
 3. The method ofclaim 2, wherein a Committed Information Rate value of the user queuefor use by the idle frame is a scheduling offset.
 4. The method of claim1, wherein the step of generating an idle frame or a series of idleframes comprises: generating an idle frame or a series of idle framesbased on a pre-configured initial bandwidth value of idle frame.
 5. Themethod of claim 1, wherein the detecting of whether the user datatransmitted to the channelized physical port reaches the backpressurethreshold comprises detecting whether a transmission buffer of thechannelized physical port reaches the backpressure threshold. 6-10.(canceled)
 11. The method of claim 2, wherein the detecting of whetherthe user data transmitted to the channelized physical port reaches thebackpressure threshold comprises detecting whether a transmission bufferof the channelized physical port reaches the backpressure threshold. 12.The method of claim 3, wherein the detecting of whether the user datatransmitted to the channelized physical port reaches the backpressurethreshold comprises detecting whether a transmission buffer of thechannelized physical port reaches the backpressure threshold.
 13. Themethod of claim 4, wherein the detecting of whether the user datatransmitted to the channelized physical port reaches the backpressurethreshold comprises detecting whether a transmission buffer of thechannelized physical port reaches the backpressure threshold.
 14. Themethod of claim 1, further comprising: after the idle frame isgenerated, if the user data transmitted to the channelized physical portstill reaches the backpressure threshold, then increasing the bandwidthof the idle frame to be combined; if the user data transmitted to thechannelized physical port does not reach the backpressure threshold,then decreasing the bandwidth of the idle frame to be combined.
 15. Themethod of claim 2, further comprising: after the idle frame isgenerated, if the user data transmitted to the channelized physical portstill reaches the backpressure threshold, then increasing the bandwidthof the idle frame to be combined; if the user data transmitted to thechannelized physical port does not reach the backpressure threshold,then decreasing the bandwidth of the idle frame to be combined.
 16. Themethod of claim 3, further comprising: after the idle frame isgenerated, if the user data transmitted to the channelized physical portstill reaches the backpressure threshold, then increasing the bandwidthof the idle frame to be combined; if the user data transmitted to thechannelized physical port does not reach the backpressure threshold,then decreasing the bandwidth of the idle frame to be combined.
 17. Themethod of claim 4, further comprising: after the idle frame isgenerated, if the user data transmitted to the channelized physical portstill reaches the backpressure threshold, then increasing the bandwidthof the idle frame to be combined; if the user data transmitted to thechannelized physical port does not reach the backpressure threshold,then decreasing the bandwidth of the idle frame to be combined.
 18. Themethod of claim 14, wherein the decreasing of the bandwidth of the idleframe to be combined comprises: decreasing the bandwidth of the idleframe to be combined to zero.
 19. The method of claim 15, wherein thedecreasing of the bandwidth of the idle frame to be combined comprises:decreasing the bandwidth of the idle frame to be combined to zero. 20.The method of claim 16, wherein the decreasing of the bandwidth of theidle frame to be combined comprises: decreasing the bandwidth of theidle frame to be combined to zero.
 21. The method of claim 17, whereinthe decreasing of the bandwidth of the idle frame to be combinedcomprises: decreasing the bandwidth of the idle frame to be combined tozero.
 22. A device for realizing backpressure of masses of ports,comprising: a detecting module, configured to detect whether user datatransmitted to a channelized physical port reaches a backpressurethreshold, and transmit a massage if the backpressure threshold isreached; an idle frame generating module, configured to generate an idleframe or a series of idle frames after receiving the message; adownstream queue scheduling module, configured to combine the idle framewith the user data which needs to be transmitted to the channelizedphysical port reaching the backpressure threshold, and transmit thecombined data; a downstream forwarding module, configured to transmitthe combined data transmitted by the downstream queue scheduling module,to the channelized physical port reaching the backpressure threshold;and a frame discarding module, configured to discard the idle framebefore the combined data enters the channelized physical port reachingthe backpressure threshold.
 23. The device of claim 22, furthercomprising: a configuration module, adapted to configure an initialbandwidth value of idle frame, enabling the idle frame generating moduleto generate an idle frame or a series of idle frames based on theinitial bandwidth value.
 24. The device of claim 22, further comprising:an upstream forwarding module, configured to forward the idle framegenerated by the idle frame generating module in an upstream direction;and an upstream queue scheduling module, configured to forward the idleframe forwarded by the upstream forwarding module to the downstreamqueue scheduling module.
 25. The device of claim 23, further comprising:an upstream forwarding module, configured to forward the idle framegenerated by the idle frame generating module in an upstream direction;and an upstream queue scheduling module, configured to forward the idleframe forwarded by the upstream forwarding module to the downstreamqueue scheduling module.